Implementation Language

A compiler can be implemented in any language we choose. For a pedagogical project it is more convenient to choose a language that is widely used, has garbage collection, and comes with excellent tools such as IDEs and Debuggers.

Production quality compilers are often written in C, C++ or Rust. For us these languages are too difficult to work with.

Lisp and Python appear to be popular languages in teaching projects. Lisp is not as widely used as we would like our implementation language to be, and dynamically typed languages such as Python are harder to work with as the project grows.

Compared to C, C++ and Rust, the programming language D appears to be much more suitable for this project, from a technical standpoint, that is. It is a garbage collection language that has less friction and is pleasant to work with. The main negatives are that it is not a popular language, and the tooling is not up to the standards of other languages.

Go would be a good candidate except that its an opinionated language that forces a certain programming model, whereas we would like a language that offers least resistance.

Java, Kotlin, Swift and C# seem like good candidates. Java has some limitations that make it harder to write memory optimized code that is often necessary in a production compiler, but we don’t care so much about that.

I decided to use Java because it is the language I am most familar with, has great tooling, and despite some short comings, is widely understood by developers around the world. My first choice would have been D if it was purely a question of technical preference.

The use of Java biases the implementation towards using some Object Orientation; this is just a consequence of the most comfortable way of expressing some designs in Java.